1. Field of the Invention
The present invention relates to an information processing apparatus for processing information according to a predetermined control program.
2. Related Background Art
In a printing apparatus which is one of the conventionally known apparatus of this kind, a predetermined control program is stored for example in an internal ROM, for controlling the apparatus.
Also in a conventional second printing apparatus, a command analyzing routine is separated from the stored program and stored in a detachable program memory medium, and plural command analyzing routines are selectively called by the main routine of a control program incorporated in the main body of the printing apparatus, whereby an apparatus can effect the printing operation according to plural command systems.
Also in a conventionally known third printing apparatus, a control program, independently executable from the control program incorporated in the printing apparatus, is stored in a detachable program cartridge, and the start-up process of the apparatus selects either to execute the control program stored on the program cartridge or to execute the incorporated program.
The program cartridge is common in shape with the font cartridge storing character dot patterns, and such cartridges have identification information indicating xe2x80x9cprogramxe2x80x9d or xe2x80x9cfont informationxe2x80x9d. The incorporated control program shifts the control to the program of the cartridge only when it bears the identification information for xe2x80x9cprogramxe2x80x9d.
However, the first conventional example mentioned above can only execute a predetermined control program, and is unable to effect the printing operation according to any other command system.
The second conventional example can adapt itself to other plural command systems, but is incapable of processes other than command analysis (changes in the control of apparatus, such as a change in the hand shake process with a data source such as a host computer, or a change or an addition in the sheet handling of the printing mechanism in a jamming process), because the main routine of the control program is incorporated in the apparatus. For this reason there is inevitably a limitation in the utilization of various printing functions by an apparatus.
Also in the third conventional example, once the execution of a control program is started, the switching of program is difficult because the other control program is so designed as to function independently from the one in execution.
Besides, in the third example, the control program on the program cartridge, which functions properly on a certain apparatus, may not function properly on another apparatus because of the difference in hardware. Consequently there is a danger that a program which does not function properly may be executed because no means is provided for identifying whether the program is proper or not.
Also in case there are certain differences in the control among plural printing apparatus, no means is provided for identifying the properly functioning programs among plural cartridges provided for each apparatus, so that an improper control program may be executed on a certain apparatus.
An object of the present invention is to provide an information processing apparatus capable of constantly executing a proper program.
Another object of the present invention is to provide an information processing apparatus capable of bidirectional program switching between an incorporated control program and a control program supplied from a detachable memory medium.
Still another object of the present invention is to provide an information processing apparatus capable of checking whether the program is switchable, in response to a request for program switching.
Still another object of the present invention is to provide an information processing apparatus capable of preventing data entry in the course of program switching.
Still another object of the present invention is to provide an information processing apparatus capable of checking whether the objective program to be switched is proper, in response to a request for program switching.
According to one aspect, the present invention which achieves these objectives relates to an information processing apparatus comprising input means for entering information; first memory means storing a first control program; second memory means storing a second control program; selection means for selecting the first or second control program; process means for processing the information, entered by the input means, according to the control program selected by the selection means; request means capable of requesting the switching to the second control program in a state in which the first control program is selected, and means for indirectly obtaining the start address of the second control program, by referring to the fixed address of the second memory means, in order to switch the control program in response to the request.
According to another aspect, the present invention which achieves these objectives relates to an information processing apparatus comprising input means for entering information; internal memory means storing a control program; plural detachable external memory means each storing a control program; selection means for selecting one of the control programs; process means for processing the information, entered from the input means, according to the control program selected by the selection means; request means capable of requesting, in a state in which one of the control programs is selected, the switching to another of the control programs; and means for indirectly obtaining the start address of the requested control program, by referring to the fixed address of the memory means storing the requested control program, in order to switch the control program in response to the request.
According to still another aspect, the present invention which achieves these objectives relates to an information processing apparatus comprising input means for entering information; internal memory means storing a control program; detachable external memory means storing a control program; selection means for selecting one of the control programs; process means for processing the information, entered from the input means, according to the control program selected by the selection means; request means capable of requesting, in a state in which one of the control programs is selected, the switching to another of the control programs; and discrimination means for discriminating whether the control program is switchable in response to the request.
According to still another aspect, the present invention which achieves these objectives relates to an information processing apparatus comprising input means for entering information; first memory means storing a first control program; second memory means storing a second control program; selection means for selecting the first or second control program; process means for processing the information, entered from the input means, according to the control program selected by the selection means; request means capable of requesting, in a state in which the first control program is selected, the switching to the second control program; and inhibition means for inhibiting the information entry into the input means prior to the switching operation of the control program in response to the request.
According to still another aspect, the present invention which achieves these objectives relates to an information processing apparatus comprising input means for entering information; internal memory means storing a control program; detachable external memory means storing plural control programs; selection means for selecting one of the control programs; process means for processing the information, entered from the input means, according to the control program selected by the selection means; request means capable of requesting, in a state in which the control program stored in the internal memory means is selected, the switching to one of the control programs stored in the external memory means; search means for searching identification information corresponding to the requested control program, on the external memory means; and means for indirectly obtaining the start address of the requested control program, by referring to a relative address to be determined from a fixed displacement from the storage position of the identification information when the information is searched by the search means.
Other objectives and advantages besides those discussed above shall become apparent to those skilled in the art from the description of a preferred embodiment of the invention which follows. In the description, reference is made to accompanying drawings, which form a part hereof and which illustrate an example of the invention. Such example, however, is not exhaustive of the various embodiments of the invention, and therefore reference is made to the claims which follow the description for determining the scope of the invention.